Do you tip the cashier at your local grocery store when they cash you out? How about the front desk clerk that's checking you in at the resort? Both of these positions make minimum wage (maybe slightly more) like the housekeepers, and they are doing you a service, yet it would never cross people's mind to tip them. Maybe the salary for a housekeeper is lower than it should be (like MANY jobs in the world) but they have union healthcare, union representation, and union contracts. Way more than many other positions see.
I have no issue with anyone who wants to tip a housekeeper - totally your prerogative and nothing wrong with it. My whole point was that tipping housekeeping is very much a Disney thing, not often seen in "the real world". Because of these boards (among other blogs), people feel compelled to tip their housekeepers, so I always like to mention it's not a tipping position like bellmen and servers who make below minimum wage and are required to report their tips.